Relapse After Allogeneic Transplantation — A New Treatment Option

Patients with hematologic malignancy who relapse after allogeneic stem-cell transplantation have limited treatment options and, in most cases, short survival.

To test whether graft-versus-tumor activity could be regenerated via an immune checkpoint inhibitor, investigators conducted a multicenter, phase I/Ib trial in which 28 relapsing patients were treated with ipilimumab (3 mg/kg or 10 mg/kg × 4 doses) followed by ongoing treatment for responders.

Among the six patients treated at the lower dose, no responses were observed. Among the 22 patients treated at the higher dose, 5 achieved complete remission (including all 3 with leukemia cutis, 1 with myeloid sarcoma, and 1 with myelodysplastic syndrome/acute myeloid leukemia), and 2 achieved partial remission (1 with Hodgkin lymphoma and 1 with pulmonary plasmacytoma). Six additional patients showed a decrease in tumor burden. Two patients developed liver graft-versus-host disease (GVHD), and one developed gut GVHD that responded to glucocorticoid therapy. Immune-related adverse events included immune thrombocytopenia in one patient, inflammatory colitis in one, and pneumonitis in one that proved fatal. Overall, five patients discontinued ipilimumab due to toxicity.